Can instant noodles with a shelf life of 12 months really do it? How to prevent free radicals like viruses?

Recently, the media interviewed the following questions:

Some imported instant noodles have a shelf life of up to 12 months, how do you do it? Why are domestic preservative-free instant noodles labeled with a shelf life of 6 months?

Similarly, the shelf life of domestic boxed pure milk is 6 months, and imported milk is 12 months, why is it so long? There are many foods that have a shelf life of at least 12 months, is this kind of thing worth buying?

In fact, what is so bad about the long shelf life of food?

The transportation time is abundant, the sales range is large, and the manufacturers are happy; the sales are less risky, the merchants are happy; the peace of mind is stored at home, and the consumers are also happy. Especially during the epidemic hoarding goods, who wants food to expire at home.

However, when it comes to food that has not deteriorated for a year or two, there are always people who feel worried: Can it really last that long? Why isn't it always bad?

People are struggling with the shelf life of food, but they are actually worried that the food will deteriorate early before the shelf life, or the quality of consumption will decline.

There are two most common causes of food spoilage: one is the deterioration caused by microbial activities, and the other is the deterioration caused by chemical reactions such as fat oxidation.

Let's start with the deterioration brought about by microorganisms.

After microorganisms multiply, there may be three kinds of trouble:

First, various enzymes will be produced, so that the smell of food changes, the taste changes, and the edible value is lost. After the daily food is left for a long time, it becomes sour, sour, and smelly, and this is the result.

Second, some pathogenic microorganisms proliferate, which may cause bacterial or viral food poisoning. For example, if someone eats food that does not seem to have obviously changed its taste, but has loss of appetite, vomiting, diarrhea, abdominal flatulence or colic, and even weakness and fever, it is most likely that this type of food poisoning has occurred.

Third, the activity of pathogenic microorganisms produces various toxins, which may cause acute or chronic poisoning. For example, events such as "eating sour soup causes the whole family to die", "eating bubble fungus into the ICU", "eating leftover noodles into the ICU", "dying after eating homemade tempeh" are mostly caused by toxins produced by microorganisms.

The easiest way to control microbes is to deprive them of the moisture they need for their activities. Or make the food particularly dry; or add a lot of sugar, a lot of salt, to the food, let the salt and sugar rob the microbial activity of the water needed.

Of course, there are other ways, such as adding a lot of alcohol to food, or adding preservatives to help inhibit the activity of microorganisms; or putting food in a freezer to reduce the proliferation of microorganisms.

Instant noodles are such a food, because they are particularly dry, and there is no way for microorganisms to proliferate in large quantities. Therefore, as long as the instant noodles are not damp, there is no need to worry about food safety problems caused by microorganisms.

But why do instant noodles have shelf life? Since microorganisms cannot reproduce, they can always be preserved, why should they be labeled with a shelf life of 6 months?

This is because there is a second cause of food corruption, that is, some chemical reactions that are not conducive to food quality, such as the most common fat oxidation reaction.

Here we focus on the fat oxidation reaction.

As long as the natural fat is placed in the place where oxygen is present, the oxidation reaction will occur automatically. It's called "auto-oxidation."

Automatic oxidation reactions are initiated by free radicals. Because of the action of light, heat, radiation, single-line oxygen, metal catalysts, etc., a very small number of unsaturated fatty acid molecules become restless, they shed hydrogen atoms, and become free radicals.

These free radicals are like the new crown virus, although the amount is small, but it is very "contagious", which will make those originally healthy fatty acids "infected" and become free radicals. Then, in a dark way, slowly begin to "spread in the community", until a large area of fatty acids has fallen, and the spark becomes a fire, as we have seen in South Korea and Hong Kong.

Fatty acids that are attacked by free radicals absorb oxygen atoms and become "hydroperoxides". It accumulates to a certain extent, and it will decompose to produce some small molecules with unpleasant odors. Then we feel the food "taste bad." As the saying goes, "hara taste", "oil consumption taste", "artemisia taste", "old oil taste", etc., are all about the taste produced by fat oxidation.

When this taste is obvious, the food is not suitable for consumption.

Oxidative spoiled food, not only does it taste bad, but also contains a lot of substances that are easy to produce free radicals, as well as toxic and harmful oxidative decomposition products. At the same time, the vitamin E and essential fatty acids that are useful to the human body will also be mostly lost.

When eaten into the body, they also promote disease and aging in the body.

It can be said that after oxidation deteriorates, food loses its health value. If you are not extremely hungry and need a little calorie to survive, do not eat these spoiled foods.

Whether it's instant noodles, cookies, potato chip pans, fried foods, peanuts, melon seeds, nuts, cooking oil and tahini... As long as it contains oil and fat, it is possible that the fat will automatically oxidize this "virus" and then deteriorate and taste.

Unfortunately, the automatic oxidation of fat is a problem that is difficult to completely solve. Whether it is dry or frozen, it cannot be completely stopped, but can only slow down its progress.

If you want to keep it longer, you have to think of various ways to slow down the automatic oxidation of this fat.

How to extend the shelf life of fatty foods?

On the one hand, it is to choose fat raw materials that are not easy to oxidize. In general, saturated fatty acids are not so easy to oxidize, and the higher the degree of unsatusis, the easier it is to oxidize.

For example, the degree of unsaturated flaxseed oil is particularly high, it is extremely easy to oxidize, and it is easier to oxidize when heated, which is not recommended to use it as a stewing pan and stir-frying. In contrast, coconut oil, palm oil, cocoa butter and other high saturation, it is not so easy to oxidize.

Therefore, many fried foods such as fried instant noodles and pan sweet potato chips like to be made with palm oil because it is cheap and stable, and the taste of frying is relatively crisp.

On the other hand, it is also necessary to make fatty acids not easy to contact with oxygen, after all, oxygen has the result of oxidation. So work packaging, tight packaging, vacuuming or nitrogen filling, plus a pack of oxygen scavengers to create a relatively safe environment for fatty foods.

In addition, it is necessary to find a way to remove metal ions that can catalyze oxidation reactions.

Reduce the effects of light, rays, and temperature in storage, as these all promote oxidation. It is wise to store in opaque packaging in a cool environment.

Finally, there is another big trick, that is, to add "antioxidants".

This additive can "extinguish" the small amount of "free radicals" that appeared in the early days in time, so as to avoid the spark from becoming a fire. Therefore, there are almost no long shelf life foods that contain a lot of fat without the addition of antioxidants. What variety to add, how much to add, or the combination of several antioxidants, there is a lot of learning.

Can the shelf life of instant noodles be extended from 6 months to 12 months?

Take the imported instant noodles marked with a shelf life of 12 months, for the media's questions, it is said that the reply given by the production enterprises is: "This product has added antioxidants."

It is true that antioxidants can delay the deterioration of instant noodles, but they cannot make food have a "not bad gold body". As long as it is long enough, the food will eventually oxidize.

Therefore, even if antioxidants are added, instant noodles still need to be marked with shelf life.

The vast majority of products are labeled as 6 months, and storage and sales practices have proved that this shelf life is no problem. Therefore, 6 months has become the industry practice.

Generally speaking, product development must determine its quality standards through various experiments, as well as the shelf life under specified conditions.

A product that is usually labeled for 6 months can not be labeled for 12 months, which requires shelf life experiments.

For example, if imported boxed milk changes from a shelf life of 6 months to 12 months, the temperature and time of sterilization need to be adjusted.

To double the shelf life of instant noodles, it may also require some adjustments to the variety, amount of antioxidants, and packaging conditions to ensure that after 12 months all indicators are qualified and there is no perceptible change in flavor. It's best to take the data out and give consumers peace of mind.

If the raw materials remain unchanged, the formula is unchanged, the packaging is unchanged, and the storage conditions are unchanged, and no shelf life experiment has been done, it is not very reliable to directly write the shelf life for 6 months and sell it.

Do you want to buy foods with longer shelf life?

This problem should be decided by consumers according to their cost performance and personal needs.

For example, for boxed milk, a longer shelf life can ensure the transportation across the ocean and the process of selling around the world, but the more powerful sterilization treatment will also bring about a decline in vitamin content and a decrease in flavor quality. Proteins may produce small amounts of "isopeptide bonds" to reduce bioavailability; lysine content may decrease due to mild Maillard reactions; and sulfur-containing amino acids may be partially lost due to heat.

So, for those who care a lot about the flavor of milk, or the nutritional quality of milk, it's good to buy fresh, chilled pasteurized milk. But if you just want to use milk for cooking, for drink making, or just want to increase some calcium and protein, don't care about vitamins, and care more about cost performance, then buying boxed milk is still very cost-effective.

Instant noodles and other products, there are many products to choose from, consumers can naturally choose according to their own wishes. If I don't need to put it for a long time after buying instant noodles, and eat them in ten days and a half or a month or one or two months, then of course, you don't have to deliberately choose products with a shelf life of one year. If it is to make a reserve for emergencies, it may be more convenient to be longer.

I am more pleased that consumers have become more and more adept at reading product labels and are more and more aware of questioning product-related information. This shows that the level of consumers has improved, which is a good thing.